Not sure if the list of icons in the first post in this thread is supposed to be exhaustive or simply representative. If that list is supposed to include all icons then possibly some are missing:

There is only one animated icon - indicating a hot topic. It is presented in red (which presumably indicates a NOT-READ state). But, in fact, there is a similar animated icon which is black and encircled in green (which presumably applies to an ALREADY-READ state). I believe this same situation occurs with the icons that are/mean the same (as above) but also include the star (indicating threads the user has posted in).

“I think that this situation absolutely requires a really futile and stupid gesture be done on somebody's part!""We're just the guys to do it.”Animal House